of chicago



Patented Jan. 27, 1931 UNITED STATES PATENT OFFICE OSCAR A. CHERRY, OF CHICAGO, ILLINOIS, .ASSIGNOR'TO ECONOMY FUSE AND MANU- FACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK CONDENSATION PRODUCT UREA AND FORMALDEHYDB Ho Drawing. Application filed June 8,

This invention relates to, the processes of making condensaton products from formaldehyde or its polymers and urea, thiourea or its derivatives, and the products made thereby. v

It has been found in condensing urea, thiourea or its derivatives with formaldehyde or its polymers, that various products are formed depending upon several sets of conditions to which the reaction is subjected which are: first, the ratio of the amounts of urea and formaldehyde employed, and secondly, upon the condition prevailing as to whether or not the condensation is conducted in the presence of an alkaline, neutral or acid solution.

It has been determined by past experiments that several different substances are formed as a result of condensing urea with formaldehyde depending upon the prevailing conditions referred to, and that among these products are the following: first, methylene urea COQTH) CH 'and' dimethylene urea CO(NCH secondly, an intermediate product formed from two molecules of urea and three molecules of formaldehyde with the elimination of two molecules of water, the formula of whichis C H N O and thirdly, monomethylol urea which is C H O N and dimethylol urea C H O N The first of these, that is, the methylene urea and the dimethylene urea are quite insoluble in all ordinary solvents and are found to decompose under the action of high temperature without melting. The second or intermediate compound is thick, white, granular precipitate which is not soluble in any solvent, but will be decomposed by strong acids and is unaffected by alkalis. The third group of monomethylol urea and dimethylol urea are both easily soluble in cold water and in alcohol but are insoluble in ether.

It is desirable in the formation of condensation products to be utilized commercially, to avoid the formation of a first and second of these products, in that they consist of minute, white granules having an amorphous structure and are infusible and in soluble in ordinary solvents and are of no known commercial value, but on the other 1927. Serial No. 196,395.

hand it is desirable to form the monomethylol urea or the dimethylol urea or a mixture of these in that these substances are soluble and form a solution which is capable of, upon subsequent heat treatment, polymerizing to form a colloid which upon a continuation of the heat treatment becomes viscid, graduall insoluble and finally gelatinized into a har insoluble, infusible vitreous mass.

In view of this, it is desirable'to note particularly the conditions which, when prevailing will promote the formation of the monomethylol urea and dimethylol urea to the exclusion of the undesirable condensation products. It has been found in the presence of slightly acid solutions that either methylene urea of dimethylene urea are formed depending upon the amount of formaldehyde employed relative to the amount of urea used, provided however, that the formaldehyde used is less than five parts to one part of urea, but on the contrary, if an excessive amount of formaldehyde, namely, approximately more than five times that of urea is employed, no precipitate is formed, but rather, a solution which is capable of being subsequently gelatinized and hardened, is formed. In addition, it has been learned that it is not necessary to use this excessive amount of formaldehyde to form an initial condensation product which is soluble, provided the solution, in the presence of which the condensing re action takes pla ce, is basic rather than acid.

As above set forth, the initial condensation product is found to be a soluble substance forming a solution which, on standing in the atmosphere or being heat treated is capable of being gradually gelatinized to form a viscid, intermediate product and finally hardened into an insoluble and infusible substance. Although, the formation when relatively small amounts of formaldehyde to that of urea are employed depends upon the addition of a base to the solution to form the initialproduct, the final hardening is accomplished by rendering a mass slightly acid which may be effected by any one of several well known methods.

Proceeding with this information, I have by distillation and also found that one of the principles which effects the condensation reaction between the formaldehyde and urea is that of the hydrogen ion concentration of the solution to which the condensation action is exposed.

I have learned further, that very desirable results can be had bythe process of condensing urea with formaldehyde in the presence of a solution, the hydrogen ion concentration of which is approximately 1 X 10-, which process constitutes the subject-matter of my co-pending ap lication Serial N 0. 193,740, filed May 23, 1-92? the condensation reaction is conducted at the hydrogen ion concentration of 1 X 10' a condensation product soluble inwater is obtained. As the reaction proceeds, this product passes into a colloidally dispersed form which is probably a hydrated form of U on removal of water nal heat treatment, a jelly-like mass is obtained which finally passes into a hard, toughened product which under some circumstances, depending-upon the particular formula employed, will be transparent.

It is important to the understandingof this invention to consider that the hydrogen ion concentration of an absolutely neutral solution is 1 X 10", and that I have found according to the present invention, as well as the one above outlined and-disclosed in. my co-pending application referred to, that it is possible to form the soluble products of condensation without resorting to the employment of basic solutions, or even neutral solutions, or to the relatively large amounts of formaldehyde heretofore employed, but on the contrary, with solutions which are in fact, acid and according to the present invention, a solution having a hydrogen ion concentration of approximately 1 X 10'.

In addition to the fact that this hydrogen ion' concentration is proper for the formation of the initial product according to the method contemplated by my invention, it is also found that acid solutions are proper for the formation of the intermediate and final products from the initial product. With this in mind, it can be appreciated that in practicing my invention, it is accordingly dimethylol urea.

unnecessary to resort to the introduction of bases but that the entire process for making the product including the initial condensation and the subsequent hardening, may be conducted in the presence of an acid solution.

It is well known that formaldehyde solutions contain in addition to formaldehyde, an appreciable amount usually about of 1 per cent by weight of formic acid, and consequently, solutions of condensation products made up solely of urea and formaldehyde are actually acid solutions which under When ordinary circumstances will have a hydrogen ion concentration of approximately 1 X 10-. As above mentioned, my invention contemplates the condensation of urea and formaldehyde in the presence of a hydrogen ion concentration of approximately 1 X 10' by a reaction in which a relatively large amount of urea, as compared with the formaldehyde, is employed or in other words, one part of urea to from one to five parts of formaldehyde.

My invention accordingly proceeds upon the principle of introducing the urea in small portlons and permitting ebullition to cease after the introduction of each portion befor'f'the next portion is introduced.

Prior to my invention, it was believed that in all instances when an amount greater than one-fourth A,) moleculeof urea is .added to one (1) molecule of formaldehyde in aqueous solution, that an exothermic reaction occurred even without the application of heat, with the formation of dehydration products of dimethylol urea, which products are granular, white insoluble bodies having no valuable commercial uses, but that, if the amount of urea is kept low, then vitreous products were obtained by distilla tion of the solution.

I have now found, however, that relatively large amounts of urea may be condensed with formaldehyde at a hydrogen ion concentra tion of approximately 1X10- without the formation of any insoluble material, provided the condensation iscarried out in accordance with my invention. Although several methods may be employed, I have for the purposes of illustration, herein given several specific methods which are known to serve well in the formation of condensation products, but which are not intended to be limitations on my invention, the scope of which is set forth in the appended claims.

It is to be understood in connection with this invention, that when I use the term urea, I mean urea, thiourea or its derivatives, and when I use the term formaldehyde, I mean formaldehyde or its polymers. The following are examples by which my invention may be practiced.

Process 1 1200 parts of 40% formaldehyde solution are heated to 9095 C. under a reflux condenser and 90 parts of urea are added. The solution is then heated to boiling. As soon as ebullition commences the heat is removed, since the reaction that occurs is exothermic, and the solution will continue to boil for some time without the application of external heat. When ebullition ceases, 90 parts more of urea are added. It is unnecessary to apply heat at this stage since the heat of reaction will cause the solution to boil spontaneously upon standing for a few minutes.

concentration of from 1 X 10' to 1 X 10'.

When ebullition-ceases, 90 parts more of urea For example, parts of urea are condensed are added and the process is continued in this with 200 parts commercial formaldehyde at manner until 500 parts of urea have been a hydrogen ion concentration of 1X10 as added, the final portion of urea added condescribed under Process 1. The successive sisting of 50 parts. portions of urea consisting of'15 parts each.

When the final portion of urea has been To the product is then added sufiicient-caustic added and has reacted, a colorless, rather thin soda or' other base'to lower the hydrogen ion liquid is obtained, which is poured into molds. concentration to 1 X10- and the roduct is Upon cooling, the product sets to a stiff gel. heated in a distilling flask until substantially Upon standing at room temperature, water all of the free water 'has been eliminated. is eliminated, syneresis occurs, and the prod- Suflicient dilute acid, either organic or inuct finagy becomes very hard, strong andorganic is then added to raise the hydrogen tough. eatirtg'at aslightly elevated temper i on concentration to 1 X 10" or more and the ature, say 50 may be resorted to, to hasten distillation is continued until the product is the conversion into the final product, but it is of the correct viscosity for casting. The cast unnecessary. This product is unaffected by articles are transformed into the final, incold water, but softened by boiling water. fusible, tough, hard, strong products by being The process diifers from that ofi prior subjected to a heat treatment ranging from known processes, especially in that the urea 50 to 100 C. over the course of several days is added gradually and in the presence of or weeks'depending upon the thickness of the sufficient acid to produce'a hydrogen ion conarticles.

centration of 1 X 10. Furthermore, another P 3 condensing agent may be substituted for the T0068? formic acid present in'commercial formalde- This is an improvement on Process No. 1. hyde solution. This step has heretofore been The process consists of'obtaining condensaunknown. tion products of urea and formaldehyde by For example, to parts of commercial causing the initial condensation to proceed at formaldehyde solution is added suflicient ala hydrogen ion concentration of 1 X 10, and kali or other base to completely neutralize the then reducing the hydrogen ion concentration formic acid. To the neutral solution is added to 1 X 10- in order to obtain the intermediate sufiicient hydrochloricv or other mineral acid condensation products.

to produce a hydrogen ion concentration of For example,to 200 parts of 40% formalde- 1X 10". Thirty 630) parts of urea are then hyde are added 75 partsof urea in portions added at 95 in portions of 6 parts in of 15 parts each in the manner described unthe manner previously described. Exactly .der Process No. 1. To the initial condensasimilar results are obtained as when formic tion product thus obtained is added 1 part acid was used as the condensing agent. The manganese acetate and the solution is disintermediate products made by the above tilled until substantially all of the uncom method contain considerable quantities of bined water has been eliminated, the residue water. In order to reduce the proportion of is cast and hardened by being heated at 60 to water present, paraformaldehyde may be used 100 C.

to replace a portion of the formaldehyde. Of course, any method of reducing the by- For example, 20 parts of paraformaldehyde drogen ion concentration to 1X10 for the are added to 80 parts of formaldehyde solusecond operation will give results similar to tion, and to the'mixture are added 50 parts those obtained by the use of maganese acetate. urea in portions of 10 parts each. The man- For example, caustic soda, sodium carbonate,

her of addition is that previously described, or hexamethylenetetramine in the proper except that the solution should be boiled a amounts may be used. trifle longer between each addition of urea. Among the advantages which are realized in practicing my invention over other known processes in the art, are first, that in the event Products made according to the preceding formaldehyde is used, the amount of water to method, contain considerable quantities of be distilled off is quite materially reduced and water and on drying shrinkage occurs. In second, clear, solutions obtained as the result some cases this is objectionable. of the initial reaction are quite stable and To do away with this undesirable feature, may be kept indefinitely without the addithe process may be carried out in three steps, tion of any stabilizing agents, this not being Process 2 namely, (1) condensation of the urea and the case of products made with an alkaline formaldehyde at a hydrogen ion concentracondensing agent which require that they be tion of 1X10; (2) distillation of the free neutralized exactly with an acid or that an water from the condensation product at a addition of a retarding agent such as sodium hydrogen ion concentration of 1 X 10- or less, acetate or sodium borate be made to keep the and (3) conversion of the condensation prodproduct from increasing spontaneously in not into the final product at a hydrogen ion viscosity; third, according to my processes, a product is formed which has a comparatively small amount of salts, alkalis or strong acids present which are highly undesirable for some purposes; fourth, the curing of the prod not to a non-vesicular mass to a great extent is facilitated b the very small ratio of for1naldehyde, con ensed with urea in the presence of an acid; fifth, distillation under reduced pressure is not absolutely necessary as in some cases, but may be desirable for the manufacture of large batches.

In general, the properties of my product are it is transparent, although it ma be rendered opaque or may be colored; it is tough, strong, insoluble in water, but softened by boiling water and infusible in the sense that it does not melt to a liquid, but decomposes in the neighborhood of 400 F. with efi'ervescence.

The term water soluble product as used above and in the appended claims, is meant to include substances held in solution either in a molecularly or colloidally dispersed form, such that they do not precipitate from the solution in which it is formed.

In the appended claims the term formaldehyde is intended to mean a40 per cent solution of formaldehyde'and in the proportions of formaldehyde and urea referred to, this should be taken into account.

I claim:

1. A composition of matter formed-by'heat treating a water soluble reaction product of 1 part of urea and from 1 to 5 parts of formaldehyde reacted in the resence of a pH of approximately 1X10, in which the urea is added and reacted in small portions at a time.

2. The water soluble reaction product of 1 part of urea and from 1 to 5 parts of formaldehyde reacted in the presence of a pH of approximately 1X10- in which the urea is added and reacted in small portions at a time.

3. A composition of matter formed by heat treating a water soluble reaction product of 1 part of urea and from 1 to 5 parts of formaldehyde in the presence of an acid solution, in which the urea is added and reacted in small portions at a time.

4. A composition 'of matter formed by heat treating a water soluble reaction product of 1200 parts of 40% formaldehyde solution and 500 parts of urea reacted in the presence of a pH of approximately 1X 10, in which the urea is added and reacted in small por tions at a time.

5. The process of forming water soluble condensation products from, 1 part of urea and from 1 to 5 parts of formaldehyde in the presence of an acid solution, which consists in addin the urea in small portions to the formalde yde, and permitting ebullition to cease after the introduction of each portion before the next portion is introduced.

6. The rocess of forming water soluble condensation products from, one part of urea and from one to five parts of formaldehyde,

. small which consists in establishing a hydrogen ion concentration of approximately 1 X 10" in the reaction solution and adding the urea in ortions.

7. he process of forming water soluble condensation products from, one part of urea and from one to five parts of formaldehyde,

which consists in esta lishing a hydrogen ion concentration of approximately 1 X 10 in the reaction solution and adding the urea in small port-ions, and permittin ebullition to cease after the introduction 0 each portion before tli next portion is introduced.

8. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximatel 1 X 10*.

9. The process 0 condensing urea and formaldehyde which consists in introducing a small portion at a time of, one partof urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1 X 10" and then hard-y ening the condensation product.

10. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1X10, and then molding and hardening the condensation product.

11. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1X10", and then hardening the concentration product by heat.

12. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1 X 10" and permitting ebullition to cease after the introduction of each portion of urea, before the next portion is introduced.

13. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1X10- and distilling off the free water from the condensation product.

14. The process of condensing urea and formaldehyde which consists in introducing a small portion at a time of, one part of urea to from one to five parts of formaldehyde in the presence of a hydrogen ion concentration of approximately 1X10 and distilling ofi the free water from the condensation product at a hydrogen ion concentration of ap-,

of approximately 1 X 10" for further treating said product.

17. The process which consists in heating 1200 parts of 40% formaldehyde solution to approximately 95 C. under a reflux'condenser and adding to the formaldehyde, 500 parts of urea in portions of approximately 90 parts each, while permitting ebullition occurring after the introduction of the portion to cease before the next portion is introduced.

18. The process which consists in heating 1200 parts of 40% formaldehyde solution to approximately 90-95 C. under a reflux condenser and adding to the formaldehyde, 500 parts of urea in portions of approximately 90 parts each, while permitting ebullition occurring after the introduction of the portion to cease before the next portion is introduced, and then pouring into molds and hardening.

19. The process which consists in heating 1200 parts of 40% formaldehyde solution to approximately 9095 C. under a reflux condenser and adding to the formaldehyde, 500 parts of urea in portions of ap roximately 90 parts each, while permitting e ullition occurring after the introduction of the portion to cease before the next portion is introduced, and then eliminating water and pouring into molds and hardening.

Signed at Chicago, Illinois, this 31st day of May, 1927.

OSCAR A. CHERRY. 

